1. Field of the Invention
The present invention relates to an active energy beam-curable composition for optical materials, and belongs to the technical field of an active energy beam-curable composition and an optical material such as a lens sheet, a plastic lens and the like.
2. Description of the Related Art
Conventionally, a lens sheet such as a Fresnel lens, a lenticular lens and the like is manufactured by molding using a method such as a press method, a cast method and the like.
However, the former press method has such problem that the productivity is low because the production is carried out by a cycle of heating, pressurizing and cooling. On the other hand, the latter cast method has such problem as an increased production cost due to a lot of necessary molds in addition to a long production time because of a process in which a monomer is cast in a mold to polymerize.
On the other hand, since an active energy beam-curable composition has quick curability and is excellent in productivity, various suggestions have been made about an active energy beam-curable composition for producing a lens sheet in order to solve the above-mentioned problems (for example, JP-A-61-177215 (Claim), JP-A-61-248707 (Claim), JP-A-61-248708 (Claim), JP-A-63-163330 (Claim), JP-A-63-167301 (Claim) and JP-A-63-199302 (Claim), JP-A denotes a Japanese unexamined patent application publication).
However, conventional active energy beam-curable compositions are insufficient in refractive index and transparency. In order to improve the point, a composition is examined in which a bisphenol-type di(meth)acrylate and a mono(meth)acrylate having an aromatic ring are used in a combination (for example, JP-A-9-87336 (Claim) and Japanese Patent No. 3397448 (Claim)).